1. Field of the Invention
The present invention relates to a circuit substrate and a method for fabricating the same. In particular, the present invention relates to a package substrate having a adjustable circuit structure and a method for fabricating said package structure.
2. Description of Related Art
In recent years, electronic devices are frequently installed in a circuit board for improving electrical properties of the electronic devices, which is known as a system-in-package (SIP) structure. The SIP structure is referred to as a system integration package. Namely, the electronic devices are compacted into a single package in which passive devices, memories, electronic connectors, and other embedded devices are included. A variety of manufacturing methods can be applied to the SIP structure made of various materials. As the electronic devices are configured within the circuit board, metal lines (conductive layers) are stacked on the circuit board through performing a build-up method, so as to assemble the circuit board having multiple layers.
Nevertheless, the SIP structure has a relatively complicated structure notwithstanding the fact that the SIP structure can effectively reduce package area and initially integrate the system. Moreover, in comparison with a single chip package, the SIP structure encounters more challenges with respect to its design for heat dissipation and maintenance of electrical reliability. In particular, the SIP structure contains a variety of embedded devices integrated in the circuit board, thus posing a limitation on the circuit layout of the SIP structure. During fabrication of the SIP structure, circuit patterns are not apt to be adjusted, and electrical performance of the entire device is relatively affected. Taking a common embedded band pass filter (BPF) as an example, the circuit acting as an inductor cannot be adjusted in a timely manner, and therefore a frequency shift is prone to occur, exacerbating the band-pass effect and deteriorating performance of the SIP structure.